This is a 3-yr, single center, open label, active controlled, randomized study of approximately 99 postmenopausal females with osteoporosis of spine or femoral neck. Patients will be assigned to 1 of 3 groups: 1) PTH 1-34; 2) Fluoride; 3) PTH and fluoride. The treatment period is 3 years with 3-month cycles of therapy. PTH will be administered subcutaneously by injection 600 units daily for 28 days the first month of each 3-month cycle. Fluoride will be administered orally one 76mg tablet twice daily (providing 20 mg fluoride/day), during the last 2 months of each cycle. Calcium will be provided 800mg/day during month 1 and 1500-2000mg for months 2 and 3 of each cycle.